1. Field of the Invention
The present invention relates to a multi-layer fuel container.
2. Description of the Related Art
For storing hydrocarbons such as gasoline therein, molded plastic containers are favorably used these days, and one example is a fuel tank for automobiles. For plastics for that use, polyethylene (especially, very-high-density polyethylene) is considered good as it is inexpensive and easy to mold and has good mechanical strength. However, fuel tanks of polyethylene are known to have a drawback in that vapor or liquid of gasoline stored therein often evaporates away in air through the container wall of polyethylene.
To solve the problem, disclosed is a method of introducing a halogen gas (e.g., fluorine, chlorine, bromine) or sulfur trioxide (SO3) into a polyethylene container to thereby halogenate or sulfonate the inner surface of the container. To facilitate the halogenation or sulfonation of the inner surface of the container, disclosed is a fuel tank for automobiles, of which the upper and lower sections both of a synthetic resin are bonded under heat and pressure with a conductor put in the bonded part of the two sections, and in which the conductor is melted under heat in the bonded part of the two sections (Japanese Utility Model Laid-Open No. 62325/1985).
On the other hand, disclosed is a method of forming a multi-layer structure of a polyamide resin and a polyethylene resin (Japanese Patent Laid-Open No. 134947/1994, U.S. Pat. No. 5,441,781). Known is a method of forming a multi-layer structure of an ethylene-vinyl alcohol copolymer (hereinafter referred to as EVOH) resin and a polyethylene resin (U.S. Pat. No. 5,849,376, EP 759,359). Also known is a multi-layer fuel tank with a barrier layer shifted to the inside thereof for improving the gasoline barrier properties of the tank (U.S. Pat. No. 6,033,749, Japanese Patent Laid-Open No. 29904/1997, EP 742,096).